XX INTRODUCTION TO BOTANY. 



the samara or kef/-fr/n'f, a nut or akcnc, having a broad wing at 

 apex or margin (as in the Ash). 

 All the above are indehiscent. 

 The principal dehiscent chy fruits arc, 



the f(i/iicl('^ a pod formed of a single free carpel, dehiscent, along its 

 ventral or seed-bearing sutui-e only (as in the Larkspur, the 

 A schp iadc(e, etc) . 



the capsule, a pod or dehiscent fruit of any compo\md pistil, whether 

 formed from an inferior or a superior ovary. The pyxi% or 

 pi/xidiain, is only a capsule which opens by a circular, horizontal, 

 nearly medial line, cutting off the u})per half like a lid. 



136. Pecuhar names given to the fruit or parts of the fruit in Crticiferec, 

 LcguminoscR, Itosacece, Ci(curbitace(C, Umbelliferce^ and some other large 

 Orders, will be explained under those Orders. 



137. The dehiscence of a capsule is said to be septicidal, when the carpels 

 separate at the line of jiuiction ; in this case the placentae are either 

 marginal, or attached to the moi-e or less inflexed margins, constituting 

 the dissepiments. The dehiscence is locuUcidal, when the margins of the 

 carpels remain joined, while the dorsal sutures split open ; in this case the 

 placentae or dissepiments will be borne in the middle of the valve. Sepfi- 

 fraejal deliiscence, in which the valves fall away, leaving persistent dis- 

 sepiments or axile placentae, may occur either in septicidal or loculicidal 

 capsules. Circular, horizontal dehiscence (as in a pyxis) is called circum- 

 scissile. "WTien in a fruit, consisting of one-seeded carpels, the carpels fall 

 away either closed or nearly closing round the seed, each segregated 

 carpel is called a coccus. 



§ 16. The Seed. 



138. A seed is the fertilized o\v\q arrived at maturity. It is almost 

 always, except in Conifers, enclosed in the pericarp. It contains, when 

 ripe, an embryo or young plant, either filling or nearly filling the cavity, 

 but not attached to the outer shell or skin of the seed ; or immersed in, or 

 lying close to, a mealy, homy, oily, or fleshy substance, called the albumen 

 or pjerisjjcrm. The presence or absence of this albumen, that is, the dis- 

 tinction between albuminous and exalbuminous seeds, is one of great im- 

 portance. The embrvo or albumen can often only be found or distin- 

 guished when the seed is quite rijje, or sometimes only when it begins to 

 germinate. 



139. The shell of the seed consists usually of two separable coats. The 

 outer coat, called testa, is usually the principal one; and in most cases the 

 only one attended to in descriptions. It may be hard and crusfaceous, or 

 thin and mcmbraitous, or thin and chartaceotis or papyraceous (like parch- 

 ment or paper), or rarely succulent. It is sometimes expanded into ivijigs, 

 or bears a tuft of hair, cotton, or wool, called a coma. The inner coat is 

 called legmen. 



140. The fuiiicle (115) or stalk by which a seed is attached to the 

 placenta, is occasionally enlarged into a membranous, pulpy, or fleshy ap- 

 pendage, which sometimes almost closes over the seed ; this is called an 

 aril. A strophiole or caruncle is a similar appendage, originating in the 

 testa. Seeds having an aril are said to be arillate. 



141. The hilum (115) is the scar left on the seed when it separates from 

 the fimicle. The micropyle (118) is the mark indicating the position of the 

 foramen of the ovule. 



142. The Embryo consists of the radicle or root-stem ; one or two coty- 

 ledons or primary- leaves (seed-leaves) ; and the jylnmnle, or first leaf-bud 

 of the yoimg plant. In many seeds, especially when there is no albumen, 

 these several parts are very conspicuous ; in others they are difiicult to dis- 



